1. Field of the Invention
The present invention relates to a device for detecting leakage of evaporated fuel in a fuel tank of an automotive vehicle.
2. Description of Related Art
Evaporated fuel leakage from a fuel tank is usually detected by detecting pressure changes in a conduit connected to the fuel tank after the fuel tank is pressurized or de-pressurized. Since, if evaporated fuel leaks together with air from the fuel tank, the pressure in the conduit connected to the fuel tank changes, the evaporated fuel leakage is detected based on pressure changes in the conduit connected to the fuel tank. An example of the leakage detector of this kind is disclosed in JP-A-2005-069102.
In the leakage detector disclosed in JP-A-2005-069102, the conduit connected to the fuel tank and a pump for pressurizing or de-pressurizing the fuel tank are connected by a pump passage that is vertically branched out from a tank passage. A sensor passage connected to a sensor chamber in which a pressure sensor is disposed is further branched out vertically from the pump passage. Therefore, a total length of the passage from the tank passage to the sensor chamber becomes long. The sensor chamber is also connected, via the pump passage, to an orifice passage where a reference orifice is disposed. Accordingly, a distance from the orifice to the sensor chamber becomes long, and there is a possibility that a difference occurs between pressures at the orifice and in the sensor chamber. Since the pump passage is disposed vertically to the tank passage and the sensor passage, a space for making the pump passage has to be secured in the detector device. Therefore, the detector device becomes large in size. Further, since one end of the pump passage opposite to the tank passage has to be closed with a stopper or the like, the number of the parts forming the detector device increases.